A little background on Marine Rotational Force-Darwin: Back in 2011, President Obama and Australian Prime Minister Julia Gillard announced U.S. Marines would be deployed to Australia in six month rotations, with the goal of establishing a rotational 2,500-person Marine Air Ground Task Force by 2016-2017.

The Australian newspaper reports it's all part of the U.S. Defense Department's effort to "rebalance" its forces to the Asia-Pacific region of the globe:

Concerned over China's growing military might and assertive stance over territorial claims in the Pacific, Washington has sought to step up its military engagement across the region and bolster defence ties in Southeast Asia.

The 1/5 will be the first battalion from California to participate in Marine Rotational Force-Darwin. The first two rotations involved Marines based in Hawaii.

Marine Forces Pacific commander Lt. Gen. Terry Robling told the Marine Corps Times the 1/5 will be based at Robertson Barracks, a major Australian Army base in Northern Territory.